Sound-recording process



April 27 1926. F. M. JOHNSON ET AL SOUND RECORDING PROCES S Filed Dec. 14, 1923 i'r ve1qzbrs PM. Ritz/COW I 'ing Processes,

Patented Apr. 27, 1926.

UNITED STATES 1,582,049 PATENT OFFICE.

FRANCIS MORTON JOHNSON AN D ADELAIDE FAUCON, OF PARIS, FRANCE.

SOUN D-RECORDIN G PROCESS.

Application filed December 14, 1923. Serial No. 680,788.

To all whom itma-g concern.

Be it known that we, FRANCIS MORTON JOHNSON and ADELAIDE FAUCON, the first a citizen of the United States of America and the second a citizen of the Republic of France, both residing at Paris, Seine Department, N o. 22 Rue des Ecoles, in the Republic of France, have invented certain new and useful Improvements in Sound-Recordof which the following is a specification- This invention relates to the recording of sounds by means of a stylus which is connected with a vibrating diaphragm and is pressed against a recording surface having a continuous movement, said surface consisting of a substance which may be engraved by the said stylus and with a second and like layer of solvent at a point close to the stylus and rearwardly of the latter, this stylus being heated in a known manner in order to soften the substance covered by the solvent.

Various methods have been proposed in which the recording surface consists of a relatively hard substance, this being temporarily softened byheat as-well as by a solvent in order that the stylus may be enabled to act upon the same, and again becoming hard in orderto preserve the shape of the traced line for an indefinite period. But such methods have not as yet succeeded in practice, the result being only a rough and irregular line or groove WhlCh will not afford the roper reproduction of the sounds, this eing probably due to the excessive soft or pasty condition of the substance when acted upon by the stylus, and to the irregularities occasioned by the solidification of the articles of the pasty sub stance thrown off by the vibrating stylus.

In the present invention these drawbacks are eliminated by coating the surface of the solid substance, for instance celluloid, with a very narrow layer of a suitable solvent, and at a point very close to the stylus and forwardly of the latter, and with a second and like layer of solvent at a. point close to and rearwardly of the stylus, the latter being heated in a known manner in order to further, soften the substance covered by the solvent.

In these conditions, the substance is softened only upon a very narrow portion which is just suflicient for the production of the undulated record groove y the stylus, and

through the wicks 10,

the surface of the groove will be made smooth as well as cleaned by the second application of the solvent, so that the sounds produced by means of the said groove will be very clear and pure. It is to be observed that the fact of rendering the band of solvent disposed upon the record surface as narrow as possible will be further advantageous in reducing to a minimum not only the amount of solvent 'in use but also the time required for its evaporation, so that in the case of a film, the latter may'be wound immediately after making the record.

Another advantage is obtained by the application of the solvent to a narrow surface, since in the case in which various lines are to be traced in juxtaposition either in spiral or in helical form upon a given'surface, we are enabled to reduce the spacing of the lines to a considerable degree, while at the same time the portion of the surface under the. action of the stylus at any moment is not subject to alteration by a previous contact with the solvents.

The appended drawing shows diagrammatically and by way of example an arrangement for sound recording by our said method.

1 is a celluloid film which is unwound from a bobbin 2 and Wound upon a bobbin 3 after passing over the guide rollers 5, 6. During its travel, the .film passes under the point of the stylus 7 which is connected with the diaphragm 8 of an acoustic receiver 9 of a known type. In front and in the rear of said stylus and close to the latter are disposed suitable moistening elements each comprising the wicks 10, 11 di sed respectively in the tubes 12, 13 leading from vessels 14, 15 containingthe solvent. The various elements are mounted in a removable manner upon a suitable frame or support 16. If desired, the flow of liquid 11 can be regulated by known closing means such as a needlevalve, not shown. The stylus 7 is heated by the passage of an electric current or by any other means.

When moving in contact with the wick 10, the film is coated with a narrow layer of solvent which will instantly soften the celluloid or other substance constituting the film. The substance thus softened is then immediately brought into contact with the heated point of the stylus in vibration, and this.

completes the softening action and forms the desired record groove. The portion thus traced will then travel under the wick 11 which cleans the groove and its edges by the solvent action of the liquid as well as by the friction contact with the said wick.

The solvents contained in the vessels 14 and 15 may have the same or different composition as required for their respective functions.

Should the device comprise various pointed members connected together and tracing a like number of similar grooves upon a. common film, we may dispose forwardly and rearwardly of each pointed member the corresponding pair of narrow moistening elements, for the application of the solvent in a series of parallel lines.

We claim A process for recording sounds upon a continuously moving surface consisting in the engraving of said surface by means of a heated stylus connected with a vibrating diaphragm and maintained in contact with said surface in order to trace thereon a'sinuous line or groove, the step of applying upon the said surface a very narrow layer of a suitable liquid solvent at a. point in close proximity to said stylus and forwardly of the same, and then applying a second very narrow layer of a suitable liquid solvent at a point in close proximity to said stylus and rearwardly of the same.

In testimony, that we claim the foregoing as our invention we have signed our names.

FRANCIS MORTON JOHNSON. ADELAIDE FAUCON. 

